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Purchase Guide: How To Choose The Right Laboratory Filters

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In the laboratory, from reagent sterilization and basic research to clinical and environmental testing, filtration is one of the fundamental steps in preparing samples for further analysis.

When choosing the right filtration system, there are a number of factors to consider that may affect the final filtration result, from material compatibility to pore size.

Sanitek summarizes 4 key points to keep in mind and walks you through the process of selecting the right filter for your laboratory use.

What is Laboratory Filtration

What is Laboratory Filtration?

Laboratory filtration is the process of filtering a sample or solution in a laboratory setting. Filtration works by passing a fluid to be separated through a filter medium, such as a membrane or other structure with micropores. The larger particles or impurities in it are held back in the medium, resulting in the separation of the particles.

Laboratory filtration is one of the basic steps in many experimental and analytical processes and is commonly used in laboratory work in fields such as chemistry, biology, medicine and environmental science.

Applications of Filtration in the Laboratory

Applications of Filtration in the Laboratory

In the laboratory, filtration technology plays a role in a variety of fields. From reagent purification to biological sample processing to solution preparation and mixture separation, as well as environmental and water quality monitoring, it is an essential and critical step.

Reagent purification and sterilization

In the laboratory, the purity and sterility of reagents are closely related to the results of experiments. Filters help remove impurities and microorganisms from reagents, including suspended solids, microorganisms, cellular debris, and more. This ensures the purity and sterility of reagents and the reliability and reproducibility of experimental results.

Reagent purification and sterilization

Biological Sample Handling

In biological research, various biological samples need to be processed, such as cell cultures, serums, bacterial cultures and so on. Through filtration, cell debris, bacteria, viruses and other impurities in the samples can be effectively removed to improve the purity and quality of the samples.

Solution Preparation and Mixture Separation

Laboratories often need to prepare various solutions or mixtures and separate them. Filtration removes solid particles or suspended matter, such as sediments or impurities, from solutions, making them clearer and more transparent and ensuring the accuracy of subsequent experimental operations and the reliability of results.

Environmental and Water Quality Monitoring

In the field of environmental science and water quality monitoring, filtration is used to collect environmental samples such as water and gas samples and remove contaminants such as particles, microorganisms and organic matter from them.

This reduces interfering substances in the samples, improves the accuracy and reliability of subsequent analysis and testing, and provides important technical support for environmental protection and water quality monitoring.

Selection of laboratory filters need to pay attention to 4 points

In the laboratory, usually filtered are organic molecules solution, or laboratory cell culture dishes and other biological products, in addition to gas environmental samples, etc., choose the laboratory filter usually need to pay attention to the following 4 points of skill. 

Point 1: Laboratory Filter Materials

The primary consideration in laboratory filter selection is the type of filter material.

Filters Material
Depth filters Typically made of thick, porous materials such as cellulose or fiberglass, they are suitable for high flow and low pressure applications. They provide effective filtration by trapping particles on the filter surface and within the structure.
Trail Etch Filters Made of high quality polycarbonate film with a variety of precise pore sizes for accurate particle separation and retention. Avoids particles from being trapped within the filter structure during the filtration process, providing higher filtration accuracy compared to depth filters.
Microfiltration membranes Typically made of various polymers with a spongy structure. Thin microporous membranes are used to separate or retain particles on the surface of the membrane, acting as a cut-off, and are mostly filter membranes with a sterilizing filter effect that strictly meets the high standards of the laboratory industry.
Ultrafiltration membranes A semi-permeable membrane designed to retain large molecules when a driving force such as pressure is applied. Ultrafiltration membranes can be used in the laboratory to separate and purify larger molecules in solution.
Chromatography Membrane Although not filters per se, they are manufactured in a similar manner to microfiltration membranes. They are highly specialized stationary phase matrices, functionalized by ion exchange or affinity ligands, used for purification and refinement of biomolecules based on their chemical and physical properties.

Point 2:  Filter Pore Size

We all know that the pore size of a filter must be smaller than the size of the particles that need to be filtered, i.e., the pore size determines the range of sizes of particles that can pass through or be trapped in the filter.

The exact pore size required for a particular application will depend on the nature of the sample, the purity required and the throughput.

In some cases, it may be necessary to perform multiple filtration steps or use filters with different pore sizes. In some cases, it may be necessary to perform multiple filtration steps or use filters with different pore sizes to ensure that higher precision filtration requirements are met and that consistency before and after filtration is achieved.

Below are common filter pore sizes for several types of filters:

  • Depth filtration(0.7-100 µm) is used to remove visible and smaller particles, or to remove cells after harvesting in a bioreactor.
  • Microfiltration (0.1-10 µm) retains particles such as bacteria, yeast and large cells in the surrounding liquid and is commonly used for clarification, sterilization and contaminant removal.
  • Ultrafiltration (1-100 nm) membranes retain large molecules such as proteins, nucleic acids, viruses and nanoparticles in liquid samples. These filters are used for concentration of biomolecules, buffer exchange and desalination, and also for protein removal.
  • Chromatography membranes (up to hundreds of nanometers) have a macroporous structure that allows purification of not only proteins and nucleic acids, but also larger protein complexes and viruses.
  • Reverse osmosis (less than 1 nm) is used to remove salts and other small molecules from water and other liquids, e.g. to prepare ultrapure water.

Point 3: Chemical Compatibility

A very important factor to evaluate when considering the choice of filter material is chemical compatibility. This involves evaluating the tolerance of the filter membrane to various substances such as acids, bases, and organic solvents.

The filter material should be chemically and physically compatible with the content and composition of the sample being filtered. For example, certain filter housings are more chemically resistant than others.

Filter materials that are incompatible with process conditions may shrink, expand or deform, for example, they are intolerant to high temperatures, repulsive to strong acids and bases, and other reasons. This ultimately leads to poor filtration or even damage to the filter.

We often see “low protein adsorption”, what does protein adsorption mean here? Some filters may be considered “sticky” to certain proteins; this means that proteins will be adsorbed to the membrane, reducing the final yield.

Sanitek offers filters in a variety of materials that can be customized to the specific chemistry of the fluid being filtered.

best capsule filters

Point 4: Filter Flow Rate

Flow rate is the speed at which a liquid or gas passes through a filter. It depends on a number of factors, including:

  • Filter Material
  • Pore Size
  • Surface Area Of The Filtration
  • Viscosity Of The Sample
  • Temperature
  • Whether To Use a Pre-Filtration Step

 

While a higher flow rate can speed things up, it may cause some damage to the filter during the filtration process, thus reducing the yield.

In order to prevent this situation, one or two pre-filters are usually added before the final filtration, which can not only quickly filter some larger particles and impurities, but also protect the subsequent sterilization filter from damage and extend the life of the filter.

In summary, the filtration flow rate is not the larger the better, according to the products to be filtered to select the appropriate filtration system can effectively ensure that the yield and purity of filtration.

Conclusion

Depending on the industry application, you may need different types of filtration products. For example, capsule filters are disposable filters that are used for laboratory filtration and also in the biopharmaceutical industry.

Pre-filters remove larger particles and impurities from liquids, and sample preparation, sterilization, and clarification of aqueous, solvent, and other liquids in the laboratory can be achieved with decontamination filters.

Sanitek offers laboratory filtration products and also offers filter testing services. If you have a need to purchase laboratory filtration products, please contact our expert team today and we will provide you with the perfect laboratory filtration solution within 24 hours.

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